Nissan Frontier. Manual - part 442

P0507 ISC SYSTEM

EC-339

< DTC/CIRCUIT DIAGNOSIS >

[QR25DE]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

OK

>> GO TO 3.

NG

>> Discover air leak location and repair.

3.

REPLACE ECM

1. Stop engine.

CAUTION:

Perform PROCEDURE AFTER REPLACING ECM. Refer to 

EC-121, "Procedure After Replacing

ECM"

.

2. Replace ECM.

>> INSPECTION END

EC-340

< DTC/CIRCUIT DIAGNOSIS >

[QR25DE]

P050A, P050E COLD START CONTROL

P050A, P050E COLD START CONTROL

Description

INFOID:0000000009481012

ECM controls ignition timing and engine idle speed when engine is started with pre-warming up condition.

This control promotes the activation of three way catalyst by heating the catalyst and reduces emissions.

DTC Logic

INFOID:0000000009481013

DTC DETECTION LOGIC

NOTE:

If DTC P050A or P050E is displayed with other DTC, first perform the trouble diagnosis for other DTC.

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following procedure

before conducting the next test.

1. Turn ignition switch OFF and wait at least 10 seconds.

2. Turn ignition switch ON.

3. Turn ignition switch OFF and wait at least 10 seconds.

TESTING CONDITION:

Before performing the following procedure, confirm that battery voltage is more than 11 V at idle.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE-I

With CONSULT

1. Turn ignition switch OFF and wait at least 10 seconds.

2. Turn ignition switch ON.

3. Select “DATA MONITOR” mode with CONSULT.

4. Check the indication of “COOLAN TEMP/S”.

With GST

Follow the procedure “With CONSULT” above.
Is the value of “COOLAN TEMP/S” between 15

°C (59°F) and 36°C (97°F)?

YES

>> GO TO 3.

NO-1 [If it is below 15

°C (59°F)]>>Warm up the engine until the value of “COOLAN TEMP/S” reaches 15°C

(59

°F) or more. Retry from step 1.

NO-2 [If it is above 36

°C (97°F)]>>Cool engine down to less than 36°C (97°F). Retry from step 1.

3.

PERFORM DTC CONFIRMATION PROCEDURE-II

With CONSULT

1. Set the select lever in N range.

2. Start the engine and warm up in idle with the value of “COOLAN TEMP/S” between 15

°C (59°F) and 40°C

(104

°F) for more than 15 seconds.

3. Check 1st trip DTC.

With GST

Follow the procedure “With CONSULT” above.
Is 1st trip DTC detected?

YES

>> Go to 

EC-341, "Diagnosis Procedure"

.

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P050A

Cold start idle air control system 
performance

ECM does not control engine idle speed properly 
when engine is started with pre-warming up con-
dition.

• Lack of intake air volume
• Fuel injection system
• ECM

P050E

Cold start engine exhaust temper-
ature too low

The temperature of the catalyst inlet does not 
rise to the proper temperature when the engine 
is started with pre-warming up condition.

P050A, P050E COLD START CONTROL

EC-341

< DTC/CIRCUIT DIAGNOSIS >

[QR25DE]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000009481014

1.

PERFORM IDLE AIR VOLUME LEARNING

Perform idle air volume learning. Refer to 

EC-124, "Idle Air Volume Learning"

.

Is Idle Air Volume Learning carried out successfully?

YES

>> GO TO 2.

NO

>> Follow the instruction of Idle Air Volume Learning.

2.

CHECK INTAKE SYSTEM

Check for the cause of intake air volume lacking. Refer to the following.

• Crushed intake air passage

• Intake air passage clogging

• Clogging of throttle body
Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Repair or replace malfunctioning part

3.

CHECK FUEL INJECTION SYSTEM FUNCTION

Perform DTC Confirmation Procedure for DTC P0171. Refer to 

EC-228, "On Board Diagnosis Logic"

.

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> Go to 

EC-229, "Diagnosis Procedure"

 for DTC P0171.

4.

PERFORM DTC CONFIRMATION PROCEDURE

1. Turn ignition switch ON.

2. Erase DTC.

3. Perform DTC Confirmation Procedure. Refer to 

EC-340, "DTC Logic"

.

Is the 1st trip DTC P050A or P050E displayed again?

YES

>> GO TO 5.

NO

>> INSPECTION END

5.

REPLACE ECM

CAUTION:

Perform PROCEDURE AFTER REPLACING ECM. Refer to 

EC-121, "Procedure After Replacing ECM"

.

1. Replace ECM.

2. Refer to 

EC-121, "Procedure After Replacing ECM"

.

>> INSPECTION END

EC-342

< DTC/CIRCUIT DIAGNOSIS >

[QR25DE]

P0550 PSP SENSOR

P0550 PSP SENSOR

Component Description

INFOID:0000000009481015

Power steering pressure (PSP) sensor is installed to the power

steering high-pressure tube and detects a power steering load. This

sensor is a potentiometer which transforms the power steering load

into output voltage, and emits the voltage signal to the ECM. The

ECM controls the electric throttle control actuator and adjusts the

throttle valve opening angle to increase the engine speed and

adjusts the idle speed for the increased load.

On Board Diagnosis Logic

INFOID:0000000009481016

The MIL will not light up for this diagnosis.

NOTE:

If DTC P0550 is displayed with DTC P0643, first perform the trouble diagnosis for DTC P0643. Refer to

EC-350

.

DTC Confirmation Procedure

INFOID:0000000009481017

NOTE:

If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at

least 10 seconds before conducting the next test.

 WITH CONSULT

1. Start engine and let it idle for at least 5 seconds.
2. Check 1st trip DTC.
3. If 1st trip DTC is detected, go to 

EC-342, "Diagnosis Procedure"

.

 WITH GST

Follow the procedure “WITH CONSULT” above.

Diagnosis Procedure

INFOID:0000000009481018

1.

CHECK GROUND CONNECTIONS

1. Turn ignition switch OFF.

2. Loosen and retighten two ground screws on the body. Refer to

EC-149, "Ground Inspection"

.

OK or NG

OK

>> GO TO 2.

BBIA0621E

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0550
0550

Power steering pressure 
sensor circuit

An excessively low or high voltage from the 
sensor is sent to ECM.

• Harness or connectors

(The sensor circuit is open or shorted.)

• Power steering pressure sensor

BBIA0614E